1. Field of the Invention
The present invention relates to a helical scan type magnetic tape recording apparatus that records a plurality of recording tracks simultaneously with a thin film multihead having a plurality of head gaps, and in which the number of rotations of a rotary drum and a tape speed are determined so as to form recording tracks having the same track pitches.
2. Description of Related Art
Conventionally, as a helical scan type magnetic tape recording apparatus, there has been proposed in, for example, the following Patent Documents 1 and 2.
Patent Document 1: Japanese Patent Publication No. Heisei-8-34025
Patent Document 2: Japanese Patent No. 2513204
In the conventional helical scan type magnetic tape recording/reproducing apparatus as disclosed in the Patent Documents 1 and 2, a multi-recording head having a plurality of heads or head gaps, and a multi-reproducing head having a plurality of heads or head gaps are disposed on a rotary drum. The multi-recording head records simultaneously a plurality of recording tracks, and the multi-reproducing head reproduces simultaneously a plurality of recording tracks.
As a recording head for a helical scan type magnetic recording apparatus, there has been proposed one that employs a thin film multi-recording head (a recording element having a plurality of heads or head gaps) using a thin film element as disclosed in the Patent Document 3, for example.
Patent Document 3: Japanese Patent Application Laid-open No. 2002-216313
A thin film multi-recording heads of the above Patent Document 3 is now described with reference to FIG. 15 and FIG. 16. A thin film multi-recording head 10 is composed of a lower non-magnetic substrate 11, a lower insulating layer 12 and a lower magnetic shield layer 13a that are laminated on the lower non-magnetic substrate 11, an U-shaped core 16a formed integrally with the lower magnetic shield layer 13a, a first thin film recording head W1 composed of a coil 17a wound around the core 16a and a protection layer 18a thereof, an intermediate magnetic shield layer 19 and a lower magnetic shield layer 13b that are laminated on the protection layer 18a, an U-shaped core 16b formed integrally with the lower magnetic shield layer 13b, a second thin film recording head W2 composed of a coil 17b wound around the core 16b and a protection layer 18b thereof, and an upper insulating layer 20 and an upper non-magnetic substrate 21 that are laminated on the protection layer 18b. The thin film recording heads W1 and W2 are formed at locations shifted in the direction of lamination.
The lower non-magnetic substrate 11 and the upper non-magnetic substrate 21 are, for example, composed of AlTiC, and the upper and the lower insulating layers 12 and 20, and the protection layers 18a and 18b are, for example, composed of alumina (Al2O3). In the first and the second thin film recording heads W1 and W2, each of the tip portions of the U-shaped core 16 becomes a lower pole 14 and an upper pole 15, and a space between the lower pole 14 and the upper pole 15 becomes a head gap g.
Also, a lower pole 14b of the second thin film recording head W2 is formed in a similar shape to that formed integrally with a lower pole 14a and the lower magnetic shield layer 13a in the first thin film recording head W1, and therefore it is laminated on an intermediate magnetic shield layer 13b. It is also possible to form the lower pole 14b and the intermediate magnetic shield layer 19 of the second thin film recording head W2 integrally (use in common).
A coil 17 is wound around the core 16, and when current flows through the coil 17, a magnetic filed is generated in the head gap g, and a recording track Tr having approximately the same track width as the width of a pair of the poles 14 and 15 (a head (or head gap) width W (see FIG. 16)) is formed on a magnetic tape.
The first thin film recording head W1 and the second thin film recording head W2 are formed such that they are shifted in a direction orthogonal to the direction of the head gap g (a direction orthogonal also to the direction of lamination), and that the end portions of the pair of the poles 14 and 15, locating on the side on which their respective end portions are adjacent with each other when viewed from the direction of lamination, are overlapped by α, as shown in FIG. 16. In accordance with the thin film multi-recording head 10, a track width Tp of a recording track Tr to be recorded can be smaller than the width W of the pair of the poles 14 and 15, thereby contributing of performing high density of recording density.
Meanwhile, if a thin film multi-recording head, in which N thin film recording heads W1 to W(N) are disposed at a high density, is mounted on a rotary drum and records on a magnetic tape by helical scanning, there occurs deteriorations in accuracy of recording track width among the thin film recording heads W1 to W(N−1), or fluctuations in track width due to the mounting accuracy of the heads that causes the fluctuations, or due to fluctuation components of the drum rotation. This makes it difficult to reproduce by a thin film multi-reproducing head.